Yellow azo dye.



UNITED STATES PATEN ()FFICE.

PAUL VOLKMANN, OF ELBERFELD, GERMANY, ASSIGNOR TO FARBENFABRIKEN VORIVLFRIEDR. BAYER & (30., 0F ELBERFELD, GERMANY, A CORPORATION OF GERMANY.

YELLOW AZO DYE.

No Drawing.

T 0 all whom it may concern:

Be it known that I, PAUL VOLKMANN, doctor of philosophy, chemist,citizen of the German Empire, residing at Elberfeld, Germany, haveinvented new and useful Imwith the diazo compounds of toluidins.

The new coloring matters thus obtained are after being dried andpulverized yellow powders soluble in water with a yellow color. Theyyield upon reduction with stannous chlorid and hydrochloric acidtoluidins and 1 sulfoaryl-3-methyl-4-amino-5-pyrazolones. They dye woolfrom acid baths yellow shades. My new dyes are characterized by theircoloring power which is more than double the strength of that of theanalogous anilin dyes; and by their fastness.

To illustrate my process, I can proceed as follows, the parts being byweight :--107 parts of paratoluidin are diazotized and the diazocompound is added to a solution of 254 parts ofl-para-sulfophenyl-3-methyl-5- pyrazolone containing an excess of sodiumcarbonate. The mixture is stirred for 4 hours and the dyestuff whichprecipitates is filtered off and dried.

It is an orangeyellow crystalline powder soluble in concentratedsulfuric acid with a Specification of Letters Patent.

Application filed. April 20, 1909.

Patented Oct. 5, 1909.

Serial No. 491,134.

yellow color. Upon reduction with stannous chlorid and hydrochloric acidthe dye is decomposed, paratoluidin and 1 parasulfophenyl-3anethyl-a-amino-5-pyrazolone being obtained. It produces onwool bright yellow level shades, fast to light. In a similar mannercoloring matters can be obtained on using other toluidins or otherl-sulfoaryl-3- methyl-5-pyrazolones. The same dyestuffs can be obtainedby at first preparing the dyes from arylmethylpyrazolones and thensulfonating the dyes thus obtained.

I claim:

1. The herein-described new coloring matters obtainable from toluidinsand l-sulfoaryl-B-n1ethyl-S-pyrazolones,which are in dry state yellowpowders soluble in water with a yellow color; yielding upon reductionwith stannous chlorid and hydrochloric acid toluidins and1sultoaryl-3anethyl-t-amino-opyrazolones; and dyeing wool yellow shades,substantially as described.

2. The herein-described new coloring mat ter obtainable frompara-toluidin and lparasulfophenyl 3 methyl 5 pyrazolone, which is indry state an orange-yellow crystalline powder soluble in concentrated.sulfuric acid with a yellow color; yielding upon reduction with stannouschlorid and hydrochloric acid paratoluidin andl-parasulfophenyl-3-methyl-4e-amino-5-pyrazolone; and dyeing wool brightyellow shades, substantially as described.

In testimony whereof I have hereunto set my hand in the presence of twosubscribing witnesses.

PAUL VOLKMANN.

\Vitnesscs O'rro KoNio,

